BOSTON (State House News Service) – Lawmakers who voted last year to index the gas tax to inflation to pay for transportation investments should not be afraid to take ownership of that vote, according to the chairmen of a committee reviewing a repeal proposal that appears destined for the November ballot.

“I can’t speak for anybody else, but I think anybody who voted for it ought to stand up and stand tall. This is an investment in the safety of our roads and the future of public transit and to not do that is irresponsible. I don’t make any apologies for the vote I cast last year and I’m happy to go before the voters and defend it,” said Rep. Jay Kaufman, a Lexington Democrat and co-chair of the Joint Committee on Revenue.

The petition to repeal the law indexing the gas tax to inflation had a hearing before the Revenue Committee on Tuesday afternoon. After proponents cleared the initial signature threshold to qualify for the ballot, the Legislature has an opportunity to act on the bill (H 3847) or else supporters will be able to go ahead and collect the remaining signatures needed to let voters decide this fall.

“I think we’ll have a discussion with members of the committee but I think even today with the testimony we heard there’s overwhelming support, at least in this room, of maintaining the indexing of the gas tax,” said Sen. Michael Rodrigues, a Westport Democrat and co-chair of the Revenue Committee.

The indexing law was part of a larger transportation financing package last year that also included a three-cent increase in the gas tax. By indexing to inflation, supporters say the state will collect up to $60 million by fiscal 2018 in additional revenue for public transit, roads and bridges and $1 billion over the next 10 years.

“The most important issue to us on the South Coast is South Coast rail and without the necessary revenues there’s no way the Commonwealth of Massachusetts was going to be able to afford to make that important investment for economic development, so certainly those that represent the South Coast are very, very comfortable with the vote we took,” Rodrigues said.

Opponents of indexing said the law absolves lawmakers from having to vote for tax increases year after year by making the increases automatic. “This is an abdication of our core responsibility as elected representatives,” said Rep. Geoff Diehl (R-Whitman), testifying before the committee.

Diehl said the automatic gas tax increases will drive up the cost of school busing, groceries and deliveries for businesses.

Supporters of the indexing law greatly outnumbered those in opposition at Tuesday’s hearing, with only Diehl and Senate Minority Leader Bruce Tarr lending their voices to the repeal effort.

Representatives from transportation and environmental advocacy groups, the Greater Boston Chamber of Commerce, the Massachusetts Municipal Association and the construction and engineering trades voiced support for keeping the law. They said the transportation financing plan that passed the Legislature last year would be unsustainable without the indexing component.

“This was quite a diverse group that isn’t always on the same page on issues,” Rodrigues said after hearing some of the testimony.

Richard O’Brien, president of the American Council of Engineering Companies of Massachusetts, said the indexing law is necessary for the gas tax to keep pace with the rising cost of construction and raw materials.

Jim Klocke, executive vice president of the Greater Boston Chamber of Commerce, called the gas tax the “best and most effective way to finance transportation” because it functions as a user fee and can be earmarked to transportation infrastructure.

Diehl acknowledged that the Legislature is unlikely to repeal the indexing law this year as it did with a sales tax on software services that was also part of the transportation financing plan, but expressed optimism about taking the issue to the ballot.

“I personally feel that once the people have this in their hands there’s no way it doesn’t pass,” the Whitman Republican told the News Service. Diehl said the ballot proponents are not against making tax revenues available for transportation, but believe the Legislature should be able to debate the issue on an annual basis.

As ballot question fuel the election cycle in 2014, Diehl said there’s no doubt it will be a factor, pointing out the gains made by Republicans in the House in 2010 after a sales tax increase the year before.

Kaufman said he would leave predictions on the likelihood of a ballot question passing to “the pollsters,” but Transportation for Massachusetts Advocacy Director Lizzie Weyant said public opinion polls have showed strong support for paying a little extra at the pump as long as the money is used for roads and bridges.

“We think it will give us another opportunity to educate the public about how this money is being used and the public was supportive of that in the past,” she said.

In a memo to Revenue Committee members considering the initiative petition to repeal gas tax indexing (H 3847), Citizens for Limited Taxation on Tuesday said the law will trigger automatic tax hikes and if it’s not repealed by the Legislature “will become a major issue leading up to the November election.”

CLT wrote in its memo to committee members, “Assuming you will be running for re-election, can you defend your position in favor of taxation without representation?”